One of the greatest benefits of 3D printing technology - the ability to make replacements or parts for household objects like toys, utensils and gadgets - may be denied to US citizens thanks to the granting of a sweeping patent that prevents the printing of unauthorised 3D designs. It has all the makings of the much-maligned digital rights management (DRM) system that prevented copying of Apple iTunes tracks - until it was abandoned as a no-hoper in 2009.

US patent 8286236, granted on 9 October to Intellectual Ventures of Bellevue, Washington, lends a 3D printer the ability to assess whether a computer design file it's reading has an authorisation code appended that grants access for printing. If it does not, the machine simply refuses to print - whether it's a solid object, a textile or even food that's being printed.

The piracy of 3D designs is an emerging concern, and 3D object sharing - rather than file sharing - sites have already sprung up. While no 3D printer maker has adopted what might be called "3D DRM", international treaties like the Anti-Counterfeiting Trade Agreement mean it is not out of the question. Clamping down on moves to 3D-print handguns may fuel such moves, for instance.

What has riled some tech commentators (here and here for instance) is the fact that Intellectual Ventures that does not make 3D printers at all, but simply trades in patent rights - a practice detractors call patent trolling.

The firm, run by Microsoft CTO Nathan Myhrvold, quietly files patents under the names of a great many shell companies (as this Stanford University analysis shows) and then licenses them to companies using the ideas it lays claim to, litigating if it has to. Intellectual Ventures is thought to hold more than 40,000 patents.

The new patent may face challenges to its validity, however, because it extends rights management beyond 3D printing to much older computerised manufacturing techniques, such as computer-controlled milling, extrusion, die casting and stamping.

Companies in those businesses are likely to have previously considered some kind of design rights authentication, says Greg Aharonian, of bustpatents.com in San Francisco. He says that museums were wondering how to protect 3D sculptures against printer piracy back in 2002 and that DRM was in the frame then. So Intellectual Ventures' claim to novelty - a key part of whether any patent is determined to be valid and enforceable - looks weak.